Although kinetic analysis has contributed many advances to the field of plasma lipoprotein metabolism, it has been applied at the level of whole animal or whole human physiology almost exclusively. With the advent of modern biochemical and cell culture techniques it has become feasible to employ kinetic modeling methods in the study of intracellular and organellar processes. This project is designed to test current theories concerning hepatic assembly and secretion of very low density lipoproteins (VLDL) and, where necessary, to propose and test modifications of these theories. We will employ estrogenized chick hepatocytes in short-term monolayer culture and a newly developed (hepatocyte-derived) cell-free system as our experimental model systems; kinetic data from both published and planned experiments using glycerolipid, cholesterol, apoprotein and oligosaccharide tracers will permit detailed quantitative tests of current paradigms. This testing will be done by expressing a proposed theory as a kinetic model and comparing its predictions to our experimental data using the SAAM and CONSAM computer programs. Finally, intracellular metabolite fluxes and compartmental contents will be calculated based on the tracer data and associated mass measurements.